1. Field of the Invention
The present invention relates to apparatus and method for manufacturing a resin molded product, and more particularly to apparatus and method for manufacturing a resin molded product that allow an efficient change of a layer arrangement when a layer configuration is significantly changed, particularly when the layer arrangement is significantly changed.
2. Description of the Related Art
In a manufacturing apparatus that molds resin molded products such as plastic films or sheets, a change of resins to be supplied to an extrusion device, replacement of an entire feed block, a change of multi-manifold dies, replacement of an intermediate plug of the feed block, or the like have been performed in order to change a layer configuration such as the number of layers, a thickness of each layer, and/or an arrangement of layers. To perform these changes or replacement, the extrusion device requires to be stopped. The temperature is usually high in a process for molding a resin molded product, and stopping the extrusion device tends to cause heat degradation of a resin in the device. Further, the resin is exposed to air when the plugs are inserted into or removed from the device for replacement or the like, thereby promoting oxidation to further hasten the degradation. Heat degraded resin mixed into a product may cause a bad product. To prevent this, the temperature of the device has been lowered to a temperature that does not tend to cause the heat degradation or the oxidation for replacement. However, when the temperature is changed, the temperature requires to be increased for reuse, which may cause significant losses of time and material.
Specifically, when the layer configuration such as the number of layers, the thickness of each layer, or the arrangement of each layer are changed, the device that molds the resin molded product has mainly three problems: (1) the significant losses of time and material, (2) the heat degradation, and (3) the oxidation due to exposure to air, and there is a need for solving these problems.
For solving the problems, there have been proposed a method in which a replaceable adapter is mounted to a side surface of a die body, and replacement of the adapter changes a lamination order or the number of layers (Japanese Patent No. 3112358), and a method in which a selector plate that can be inserted or removed through a side surface is mounted between a junction block and a die, and replacement of the selector plate changes the number of layers or use/nonuse of an extrusion device (Japanese Patent Publication No. 6-55402).
However, the method in which the adapter is mounted to the side surface of the die body requires lowering the temperature of the device to a temperature that causes no degradation of resin when the adapter is replaced, which cannot eliminate the significant losses of time and material.
The method in which the selector plate that can be inserted or removed through the side surface is replaced tends to cause leakage at a connection between the junction block and the die, although the selector plate itself is compact and lightweight, and tight fastening for preventing the leakage requires much labor in next replacement.
In particular, the conventional methods cannot accommodate significant changes of the layer configuration such as a change of a layer arrangement from edge lamination in which a resin different from a resin at a center is placed at both ends of a resin molded product, to another layer arrangement, or vice versa.